SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb99a68361e1fce59d7f45bc3077d16016e9b98257316f8d64e7a84458e34ece' 
  AND token = 'ljwJe3gDvZy8KpBPJRMMzwLC8w1dGpmNeZjDeXt3VgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}